Conventional ring add/drop multiplexers (ADMs) support only a single type of ring and only one ring per network element: A user deploys and interconnects a number of different network elements at each location, using the quantity of each type of system needed for the application.
The use of a separate network element for the interface to each ring terminated at a location requires additional interfaces to interconnect the separate network elements and the additional common equipment and operations interfaces for each separate network element. The cost, space and power for these additional interfaces and common equipment can be saved by consolidating the Ring ADM functions into a single network element which also supports the DCS function.
However, this savings could be outweighed by the disadvantages of under-utilized equipment, limitations in networking capabilities, operational inconsistencies, or tradeoffs between the flexibility and simplicity of cross-connection and path-protection operations, which, if not addressed, would stem from the consolidation itself. For example, stranding of unused ports and cross-connect capacity would result from inflexibility in provisioning different types of network configurations (e.g., 4-Fiber BLSR/MS-SPRing, 2-Fiber BLSR/MS-SPRing, SONET 1+1 line protection, SDH 1+1 multiplex section protection, or 1×N/1:N line protection) independently for each of the ports in the system (including the ports on different port units within a shelf and also the multiple ports on the same optical port unit). Inefficient port utilization resulting from this inflexibility would lead to reduced system capacity and/or the need for additional equipment.
Advanced networking capabilities become possible with the consolidation of various network configurations in a single network element, but they can be realized only if the system can support sufficient flexibility in provisioning the network configuration for each port and the cross-connections for each tributary.